平衡态与理想气体

压强低温度高-–—分子间相互作用力小，热运动是主导因素。

等压膨胀系数

\[\alpha = \frac{1}{l}\left( \frac{\partial l}{\partial T} \right)_p, \ \beta_p = \frac{1}{V}\left( \frac{\partial V}{\partial T} \right)_p, \ \beta\approx 3\alpha\]

等温压缩系数

\[\kappa_T = -\frac{1}{V}\left( \frac{\partial V}{\partial p} \right)_T\]

相对压缩系数

\[\alpha_V = \frac{1}{p}\left( \frac{\partial p}{\partial t} \right)_V\]

理想气体状态方程

\[pV = \nu R T = \frac{N}{N_A}RT = NkT\] \[\Rightarrow p = \frac{N}{V}k_B T = n k_B T\]